A study found 2.4 million Scots were risking their safety. The findings by Carbon Monoxide - Be Alarmed! have been published the day before the installation of carbon monoxide alarms becomes compulsory in Scotland when a fuel-burning appliance is fitted.
Catherine McFerran and Katrina Davidson from Northern Ireland, who lost their sons in 2010 to carbon monoxide poisoning, are supporting the campaign. They said: "Carbon monoxide alarms are now compulsory ... when new appliances are installed in Scotland, but many people in older homes or in the rest of the UK may still be at risk."